Combined magnetic compass and directional gyroscope



y 14, 1940- J. RATEAU I 2.200.431

COMBINED MAGNETIC COMPASS AND DIRECTIONAL GYROSCOPE Filed May 19, 1937 4 Sheets-Sheet l INVENTOR IM WQWM ATTORNEYS y 14, 1940- J. RATEAU 2.200.431

COMBINED MAGNETIC COMPASS AND DIRECTIONAL GYROSCOP E Filed May 19, 1957 4 Sheets-Sheet 2 INVENTOR. W

W m)? Wow ATTORNEYS y 1940- J. RATEAU' 2.200.431

COMBINED MAGNETI C COMPASS AND DIRECTIONAL GYROSCOPE Filed May 19, 1937 4 Sheets-Sheet 3 IN VENTOR.

ATTORNE Y5 May 14, 1940.

J.RATEAU COMBINED MAGNETIC COMPASS AND DIRECTIONAL GYROSCOPE Filed May 19, 1937 vvvvv 4 Sheets-Sheet 4 IN VEN TOR.

ATTORNEYS Patented M014, 1940 g 2,200,431

COMBINED MAGNETIC COMPASS AND DIRECTIONAL GYROSCOPE Jacques Rateau, Montrouge, France Application May 19, 1937, Serial No. 143,607

In France May 26, 1938 Claims. (Cl. 33-204) It is known that a magnetic compass is sub- These means are preferably such that 6 being ject to oscillations due to the disturbances to the directional angle and r the action to which which the vehicle carrying it is exposed. The the controls are subjected, for example the andirection followed by the vehicle is, at any mogular displacement thereof, these two quantities 5 ment, the mean of the indications of the dial. shall be interlinked by a diiierential equation of ii On the other hand, if the axle of a gyroscope the form:

of three degrees of freedom retains a fixed direction during a certain time and makes it possible ai s-F bg-i-c0=d.r'+e.r" theoretically to determine the variations of course, the indications of the gyroscope are up- In this equation, the terms are as follows: i

set in practice by the precessions which are due to friction and other undetermined and irregular a=mment of mama causes b=dampening,

1 The invention has for its object to provide a d and gggg s g z 5 magnetic and gyroscopic compass in combination, and THIaCWm rudders 16 which enables the obviation of the defect in- T herent in magnetic compasses and in gyrosoo s The convenient choice of coefilcients enable employed independently of one another. The damping of the oscillations of the body in mocharacterlstlc feature of this compass is that tiOh a ou d the p sed direction. it being D the dial is rendered subservient to the gyroscope s b e to make he cce c e t 8 equal 20 in such a manner that at each deflection of the In O e em od ment o Suc '8 de an elecdial the axle of the gyroscope or th inner ring tric current is generated, the intensity 1 of which of the universal joint carrying this axle (the s p p o al to t e d ec al M 8 ring pivoted around a vertical axis) shall be subexampl a Screen i a h to the xl 0i Ject to a couple proportional to said deflection. the gy c p having P- Blct the width of which Moreover, by the attachment of conveniently varies in'propc i 0 e ec a mal and eccentric masses to the exterior frame of the through which 8 Pencil f light generated y a universal mounting of the gyroscope (the frame rc fix d 0 h o y in m i n reaches a pivoted around a horiontal axis), a pendulum photo-electric cell 8180 fi d 0 t y in moment is imparted to the gyroscopic assembly motion. 0

around said axis, and "the oscillations of said or produc g c re s ep esen z e assembly are powerfully braked by a appropricessive derivatives of the current i, as a function ate damper, in such manner that their period f tim t r ar p d. according to the shall be great relatively to the period of oscillainvention. for e d two three election of the dial. trode valves, the first of which receiveson its 35 If the dial performs a series of oscillations in K tehsich p p a t e ur ent to be one direction and the other from its normal derived, its Plate circuit e n c ed to the position, the axle of the gyroscope is subjected P y O an iron a s e the S d y to alternate couples, the mean of which is zero. 01 which s connected o the 8 d e Seccnd 40 The gyroscope tends to perform processions valve. The current resulting from the addition 40 around the horizontal axis of the universal f e c en s hus Obt d. i h are specmounting, but these very slow and alternate tively p o a to precessions have no time for becoming rough. do (110 In fact, the axle of the gyroscope remains parand a allei to a fixed direction, for example to the as magnetic north, and consequently permits the 1 acts upen a motor ihsllch B manner 88 to od fy direction to be ascertained at any moment. It its speed accordin o 8 linear law. This motor is suflicient to fix to the axle of the gyroscope or may be mechanically p ed o O Or of conthe inner ring of the universal mounting a needle smut Speed thmulh 8 difl'clcntifllthe e of moving opposite a scale carried by the body in which is to the l motion. The following description, in which reference For obtaining automatic piloting with the aid is had to the accompanying draw gs. EiVeh by of this device means acting upon the controls way of example, will make it quite clear in what in accordance with the directional angle indimanner the invention is to be carried into effect.

cated by the gyroscope are associated therewith. Fig. 1 shows diagrammatically, in sectional 5 elevation, the combined compass according to the invention.

Fig. 2 is a perspective view of the gyroscope and its frame, associated with a device whereby a current proportional to the directional angle may be generated.

Fig. 3 is a plan view on a larger scale of the dial of the magnetic compass.

Fig. 4 shows diagramatically the relays connected to the photo-electric cell associated with the dial.

Fig. 5 is a diagrammatic view of a valve arrangement, making it possible to obtain derivatives of the generated current and to cause their sum to act upon the controls.

Fig. 6 shows a modification of this arrangement.

Fig. 7 shows a modification of the gyroscopic mounting.

Fig. 7a is a detail view of disc 89 and its winding.

In the drawings l indicates the dial of the magnetic compass, which is freely movable in the interior of a box 2. On its periphery this dial forms a screen influencing the pencil of light emitted by a projector 3 and reflected towards a photo-electric cell 4 by a frusto conical mirror 5. The pencil of light issues from the projector 3 through a vertical slot 8, in such a manner that after reflection the horizontal section of the pencil of light is a small straight band located in a plane passing through the axis of rotation of the dial.

As will be seen in Fig. 3, the periphery of the dial is cut away over half of the circumference. Thus, the dial produces upon the pencil of light three different effects, according to the position which it occupies with reference to the assembly of cell and projector. In position I only part of the luminous flux arrives at the cell 4, in position 11 the whole of the luminous flux is arrested by the dial which is not transparent, in the position III the whole of the luminous flux impinges upon the cell. The assembly of cell and projector is fixed to a plate I, which is rotatable around the axis of the dial with reference to the box 2. This plate I is provided on its periphery with teeth meshing with a pinion 8 keyed to a shaft 9. This shaft in turn is connected for rotation to the shaft III of a small electric motor I I. The current passed by the photo-electric cell 4 is amplified by a valve arrangement, not shown, and then acts on relays controlling the electric motor II which is rotatable in both directions. When the pencil of light is in the position I with reference to the dial the motor is stopped, but in all other positions the motor H determines the rotation of the plate I and of the assembly of cell and projector in a direction such that the pencil of light shall be returned into the position I, which is the position of equilibrium. Thus, the assembly of projector and cell always turns through an angle equal to the angle of each displacement oi' the dial, in such a manner as to retain a fixed position with reference to the dial.

The relays controlling the motor I I may be arranged as shown in Fig. 4. The motor I l, the armature of which is indicated at H, has two field windings II and Il. According to whether neither of these windings is excited or one of them is excited, the motor H is stopped or rotates in one direction or the other. A relay Q has two windings e e wound in opposite directions. When the currents passing'through these windings are equal, the armature q of the relay Q is at rest, neither of the relays Q, Q is excited and the motor I l is stopped. On the contrary, when one of the currents passing through e or e predominates, one of the relays Q or Q is excited and the motor II is started up in one direction or the other. One of the windings e is connected to the grid and the other to the plate circuit of a thermionic valve 1. To the winding e is furthermore connected a source s with control resistance p. The circuit of the cell 4 is connected to the grid of the valve 1, in such a manner that the tension thus supplied to the grid shall be proportional to the current supplied by the cell.

For convenience of regulation the currents passing through c and e will balance one another in the position I of the dial, while one or the other of these currents will predominate in the positions II and III of the dial.

The motor II also drives through a worm I! a worm wheel I; which supports a gyroscope l4 driven, for example, electrically. The rotations of this wheel I! are therefore equal to the rotations of the dial and the wheel operates as a repeater of the displacements of the dial.

The gyroscope is supported by this wheel through the universal mounting rings l5 and I6, which are respectively rotatable around the axes A B A -B (Fig. 2), these being perpendicular with reference to one another. In principle the axis A B is intended to be vertical and the axis A=-B to be horizontal. A torsion spring I1 is interposed between the rings 15 and I6. Masses l8 are fixed to the ring It, in such a way that the system l4, l5, l6 shall have a pendulous moment around the axis A B. The oscillations of this system are damped by the displacement of oil contained in two tanks I! fixed to the ring IS, on respective sides of the axis Il -B and communicating through the narrow tubes 20. The whole of the masses and damper are calculated in such a manner that the period of oscillation around A=B shall be large relatively to the period of oscillation of the dial.

It will be seen that during the oscillations of the dial I, which determine the corresponding oscillations of the wheel I3, the ring I! carrying the gyroscope is subjected, owing to the provision of the spring l1, to alternate couples, which tend to produce precessions periodically inversed, by pivotal action around the axis A -B'. These precessions being very slow, they have no time to develop between two oscillations of the dial, and the axis A-B of the gyroscope preserves a fixed direction giving the directional angle.

For repeating this angle at a distance the device shown in Fig. 2 may be adopted.

A horizontal screen 2|, fixed to the ring II, carries a slot bounded on one side by a circular are 22 having is centre on the axis IL -B and on the other side bya portion of an Archimedean spiral 23, also having its pole on said axis. A projector 24 fixed to the body in motion projects upon this slot a pencil of light which is very fiat, and the horizontal section of which, when extended, is substantially a straight line passing through the axis A B The luminous flux passing through this slot is therefore proportional to the directional angle 9. It is received by a photo-electric cell 25 which generates a current i also proportional to this angle.

For the automatic piloting, currents i are caused to act upon the controls in such a manner that the action r upon these controls shall be a function of 0. This has the defect that parasite beats are produced, 0 oscillating to one side and the other of the value which it is desired to have, and further that errors are introduced due to any systematic disturbing causes. Finally, such a manner of subjection does not ofier any flexibility in the case of violent atmospheric disturbances.

According to the invention, the subordination obeys a diflerential equation of the form wherein a, b, c, d, e are constants. Thus a relation may be obtained between 1' and 0 damped as much as may be desired, so that if the body in motion is deflected from the assigned directional angle itreturns to same without per-' forming parasitic oscillations. Moreover, owing to the absence of r from the equation of subordination the errors of direction are integrated and consequently corrected by the device, which renders systematic errors impossible. Finally, by the convenient choice 01' the coeflicients a, b, c, d sufllcient flexibility may be obtained in the case of violent disturbances.

First an embodiment will be described wherein e=o.

From the current i currents proportional to the derivatives di d i a and a are generated, the coeflicients ofproportionality being calculated so as to introduce the factors 0, b, a; the three currents are then added up and in this manner a resultant current is obtained, which represents the first member of the equation of subordination. Let this current be I, then I=d.r'. The action r upon the controls is then given by r=kfIdt An embodiment is shown in Fig. 5. The cell 2.5 feeds a resistance 26 in such a manner that the tension at the terminals of this resistance is proportional to i, i. e., to 0. This tension is applied to the grid of a three electrode valve 21, which this supplies in its plate circuit a current proportional to 0 (the valve 21 operates in the linear part of its characteristic), this current flows through the primary of an iron transformer 23, the magnetic circuit of which includes a very large air gap, so that the reluctance R of this circuit is constant and equal to the reluctance of the air gap.

to being the flux, the tension e at the terminals or the secondary is therefore, at open circuit,

Now, it n indicates the number of turns of th secondary, we have: 1.25 ni=R i. e., =ki and di a zero). In the plate circuit of this valve a current di 1 =k az is obtained.

A current proportional to the second derivative is obtained in the same manner with the aid of the transformer 30 and the valve 3|. Three tensions proportional to i,

di db 3- and 3?;

are finally supplied to the grid 01' the exit valve 32 by the conductors 21', 29 and 3!- and finally in the plate circuit of this valve the current I required is obtained. Conveniently calculated resistances 21 28 3| enable the coefllcients a. b, c, to be introduced.

A motor 33 has two field magnets 34, 35. The magnet 34 is connected to a suitable source and is shunted across the armature 36, while the second magnet 35 receives the current I coming from the valve 32. In this manner the speed of the motor is proportional to I. This motor is connected to a second motor 31 of a single field magnet and rotating at a constant speed, with the aid of a diiferential 38. For a current I corresponding to the correct direction the two motors rotate at the same speed and the cage 33' of the differential remains stationary. If the luminous flux varies, the current I is modified and the speed of the motor 33 varies. The cage of the differential then rotates at a speed proportional to the diflerence of the speeds of the two motors, i. e., to I. The angle of rotation of the cage is finally proportional to J Idt and therefore it is suflicient to connect this cage to the controls for obtaining the desired subordination.

A modification will now be described, wherein w 0, so that the diflerential equation of subordination is as follows:

This current flows in a circuit including a choke (resistance R, choke L) in parallel with a resistance R The current I is divided into two currents i and i, so that:

242 R R dt Arranging the values R R L we have Considering Equation 1 it is sumcient to put r"=i=.

Integrating the value or i we obtain the value or r to be applied to the controls.

Embodiment shown in Fig. 6.

In the plate of the flnal valve 32 the circuit comprising the resistance R, indicated at ll in Fig. 6 and the choke LR. indicated at 42 is disposed. With the choke there is connected in series a resistance 43 of value 1', at the terminals of which the tension is n, and therefore proportional to i This resistance is inserted into the grid circuit of the additional valve 44, in the plate circuit of which is included the field magnet 35 of the motor described above.

The choke L may also be replaced by a condenser of capacity C.

it is sufficient to put r=i The embodiment will be analogous to the preceding one.

It is obvious that the embodiments described are examples only and that others could be imagined without departing from the scope of the present invention.

Fig, '7 shows a modification of the gyroscopic element, which enables the gyroscope to be rendered independent when the body in motion (for example an airplane) performs complex evolutions vertically. The masses l8 of the ring l6 are replaced by a disc 39 rotatable around the axis A -B and carrying an extra load, so that its centre of gravity shall be considerably eccentric. This disc 39 is mounted on ring l6 and carries a winding through which flows an electric current which fixes it magnetically to the ring l6 during normal operation, in such a manner that the assembly I4, [5, I6 shall have, as previously, a period of oscillation around the axis A -B This axis Ai -B is supported by a frame 40, which is rotatable with reference to the wheel l3 around the axis A -B which is substantially vertical. During normal operation this frame is fixed with reference to the wheel l3, for example by means of a locking device 4|. The apparatus then operates in the manner described above.

If the airplane performs complex evolutions in the vertical direction, it is sufficient to out OK the current from the disc 39 so as to release it, then to release the lock H. At this moment the spring I! interposed between the frames I5 and ii of the universal mounting is rendered inoperative, since the frame 40 is no longer fast with the wheel l3. -When the evolutions are terminated the gyroscope is returned into its initial position, if it has deviated therefrom, by displacing the frame 40 by hand so that it shall be located in the plane of the lock II, the frame 40 being then looked once more.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. An apparatus of the class described, comprising a magnetic compass having a dial, a gyroscope having a supporting shaft, a photoelectric cell, means for projecting a beam of light on said cell, means for supporting said cell and light-projecting means for rotation about the axis of the compass dial, means carried by said dial and interposed between the cell and projecting means for variably modifying the intensity of said beam of light, a motor controlled by said cell for rotating the support of the cell and light-projecting means about the axis of said dial in an amount and direction corresponding to the amount and direction of rotation of said dial so that the beam of light will always pass through the same point on the dial, and means actuated by said motor for effecting angular displacements of said gyroscope about the axis of its shaft corresponding to the mean displacements of said dial.

2. An apparatus of the class described, comprising a magnetic compass having a dial, a gyroscope having a supporting shaft, 9. photoelectric cell, means for projecting a beam of light on said cell, means for supporting said cell and light-projecting means for rotation about the axis of the compass dial, means carried by said dial and interposed between the cell and projecting means for variably modifying the intensity of said beam of light, a motor controlled by said cell for rotating the support of the cell and light-projecting means about the axis of said dial in an amount and direction corresponding to the amount and direction of rotation of said dial so that the beam of light will always pass through the same point on the dial, means actuated by said motor for effecting angular displacements of said gyroscope about the axis of its shaft corresponding to the mean displacements of said dial, and a torsion spring interposed between said gyroscope and its supporting shaft for transmitting rotary motion of said shaft to said gyroscope.

3. An apparatus of the class described, comprising a magnetic compass having a dial, a gyroscope having a supporting shaft, 9. photoelectric cell, means for projecting a beam of light on said cell, means for supporting said cell and lightproJecting means for synchronous rotation about the axis of the compass dial, means carried by said dial and interposed between the cell and projecting means for variably modifying the intensity of said beam of light, a motor controlled by said cell for rotating the support of the cell and light-projecting means about the axis of said dial in an amount and direction corresponding to the amount and direction of rotation of said dial so that the beam of light will always pass through substantially the same point on the dial, means actuated by said motor for effecting angular displacements of the supporting shaft of said gyroscope in an amount corresponding to the mean displacements of said dial, and a spiral spring connecting said gyroscope and its supporting shaft to subject the gyroscope to alternate couples.

4. An apparatus of the class described, comprising a magnetic compass having a dial, a gyroscope having a supporting shaft, a photoelectric cell, means for projecting a beam of light on said cell, means for supporting said cell and light-projecting means for synchronous rotation about the axis of the compass dial, means carried by said dial and interposed between the cell and projecting means for variably modifying the intensity of said beam of light, a motor controlled by said cell for rotating the support of the cell and light-projecting means about the axis of said dial in an amount and direction corresponding to the amount and direction of rotation of said dial so that the beam of light will always pass through substantially the same point on the dial, means actuated by said motor for effecting angular displacements of the supporting shaft of said gyroscope in an amount corresponding to the mean displacements of said dial, a frame carried by the supporting shaft of the gyroscope, a second frame, means for pivotally mounting the second frame for movement about a horizontal axis in the first frame, a third frame, means for mounting the gyroscope for rotation about a horizontal axis in the third frame, and means for mounting the third frame for movement about a vertical axis in the second frame.

5. An apparatus of the class described. comprising a magnetic compass having a dial, a gyroscope having a supporting shaft, 9. photo-electric cell, means for projecting a beam of light on said cell, means for supporting said cell and lightprojecting means for synchronous rotation about the axis of the compass dial, means carried by said dial and interposed between the cell and projecting means for variably modifying the intensity of said beam of light, a motor controlled by said cell for rotating the support of the cell and light-projecting means about the axis of said dial in an amount and direction corresponding to the amount and direction of rotation of said dial so that the beam of light will always pass through substantially the same point on the dial, mleans actuated by said motor for effecting angular displacements of the supporting shaft of said gyroscope in an amount corresponding to the mean displacements of said dial, a frame carried by the supporting shaft of the gyroscope, a second frame, means for pivotally mounting the second frame for movement about a horizontal axis in the first frame, a third frame, means for mounting the gyroscope for rotation about a horizontal axis in the third frame, means for mounting the third frame for movement about a vertical axis in the second frame, two eccentric masses carried by the second frame for imparting a pendulous effect to the latter, and a damper, consisting of two oil reservoirs communicating through a narrow tube, mounted on said third frame.

' JACQUES RA'I'EAU. 

